Training aid for pedal powered apparatus

ABSTRACT

A removable training aid for a human powered vehicle of the kind in which a pair of opposed cranks are provided which rotate relative to a common axis, the aid providing an audible or tactile indication in use that a rider is rotating the pedals by applying an incorrect pedalling technique, the removable training aid comprising an intermediary body, attachment means for attaching the body to at least one of the cranks and a pedal secured to the intermediary body, the removable training aid being arranged so that in use the pedal is free to rotate around an axis of rotation that is parallel to the common axis, the intermediary part permitting movement of the axis of rotation of the pedal relative to the crank through at least one degree of freedom in the event that a force is applied to the pedal along a path that is not perpendicular to an imaginary line that connects the axis of rotation of the crank with the threaded bore in the crank.

The present invention relates to training aids for a pedal powered apparatus such as a human powered vehicle, especially for improving the pedalling technique of a rider of a pedal powered vehicle such as a bicycle.

To achieve motion the majority of human powered vehicles utilise a pair of cranks as shown in FIG. 1 of the accompanying drawings. Two cranks 3 aligned typically 180 degrees apart and are fixed for rotation about a common axis 5 to convert a force applied by the rider into a torque. A sprocket or wheel 2 fixed to the crank mechanism and rotating about the same axis as the cranks transmits the torque to the driving wheel(s) via a chain, belt or drive shaft. Pedals 1 are typically used to enable the rider to apply a force to the cranks using his or her feet and legs, although in some specialised cases handles may be provided which allow the crank to be turned using the force of a riders arms.

Novice bicyclists have poor pedalling technique. The most common fault is to apply force only with one leg at a time on the “downstroke” of the pedals. Another common fault is to pedal by simply pumping the legs “up and down” like pistons, so that force is only applied in a vertical plane. When considering the plane looking down the axis of the crank, marked by the dash-dot line X-X′ in FIG. 1, optimum efficiency is achieved when the force exerted by the rider is perpendicular to the cranks, and in the direction of motion of the pedals. This is shown by the dashed line marked Y-Y′ in FIG. 1. The greater the angle the applied force deviates from the optimum ninety degrees the greater the inefficiencies. If the force vector is parallel to the crank the rider will be using energy due to the nature of human muscle, but none of this energy will be converted to kinetic energy in the vehicle. Maximum inefficiency would be achieved when the force applied is 180 degrees to the optimum, in this instance the rider is using energy to resist the circular motion of the crank.

According to a first aspect the invention provides a removable training aid for a human powered vehicle of the kind in which a pair of opposed cranks are provided which rotate relative to a common axis, the removable training aid comprising an intermediary body, attachment means for attaching the body to at least one of the cranks and a pedal secured to the intermediary body, the removable training aid being arranged so that in use the pedal is free to rotate around an axis of rotation that is parallel to the common axis, the intermediary part permitting movement of the axis of rotation of the pedal relative to the crank through at least one degree of freedom in the event that a force is applied to the pedal along a path that is not perpendicular to an imaginary line that connects the axis of rotation of the crank with the threaded bore in the crank.

The attachment means will typically comprise a threaded shaft that is secured to the intermediary part and permits the part to be removably secured to at least one of the cranks by engagement with a corresponding sized threaded bore in the crank. This allows the device to be easily removed from the crank. The intermediary body will then be located in a plane parallel to the plane of the crank.

In an alternative, the intermediary body may be located in the same plane as the crank within an opening in the crank and the attachment means may comprise a bearing assembly which is located around the intermediary body and which engages with the opening.

The training aid of the invention adds one or more additional degrees of freedom between a pedal and the crank, whereas a conventional pedal assembly has no additional degrees of movement and can only rotate about its axis. If the force exerted by the rider at the pedal is perpendicular to the crank no displacement in the additional degree of freedom results. If the direction the force is applied at the pedal deviates from this optimum angle the additional degree of freedom will allow additional movement between the pedal and the crank arm. The rider will be able to identify when the force applied is not in the optimum direction as they will be able to feel this movement the additional degree of freedom permits. The additional movement will be particularly evident when the crank is in the 6 O'clock position if the rider is still applying the force in the vertical downward direction, as the effective length of the crank will be increased causing the leg to extend further than normal. If the extent of the riders seat is set up such that during normal pedalling their leg is at full extent, then when the effective length of the crank is increased it will cause the rider to rock and shift position on the saddle.

Through progressive training the rider with learn to pedal in a more perfect circular motion, as to minimise the addition movement the device permits. This should lead to better pedalling efficiency when the training aid is removed.

The invention provides a means for the rider of any human powered vehicle that utilises a crank system rotating about a common axis to determine if their technique is efficient. If there are errors in the rider's technique the device will enable the rider to determine at what part of the crank's revolution there are inefficiencies. The invention also enables the rider to practise and improve their technique whilst constantly monitoring and evaluating efficiency and technique.

The threaded shaft which permits the training aid to be secured to a crank may have a right hand thread or a left hand thread. This will enable it to be used with almost all modern “off the shelf” bicycle cranks which are arranged to receive standard threaded pedal spindles. It is common for one crank to have a left hand thread and the other a right hand thread.

The training device may include a resistance means which prevents movement in the additional degree of freedom unless the component of the riders pedalling force applied is sufficient to overcome the resistance means.

The resistance means may be arranged to substantially prevent movement about the additional degree of freedom until the force applied by the rider to the pedal in that direction exceeds a predetermined level. It may, for example, be set with a threshold torque of around 5 Nm. Once that level is exceeded the resistance means may be overcome and the pedal may move. The amount of movement, or rate of movement, or noise produced by the movement should then be sufficiently large that it can be felt/heard by the rider.

Alternatively, the resistance means may progressively oppose the force such that the amount of movement permitted is a function of the magnitude of the component of the force in the direction of freedom. This ensures that the amount of movement is dependent of the magnitude of the force component. This will enable a rider to identify the points in the pedal stroke where the most force is being “wasted” by bad technique.

The resistance means may act between a part of the threaded shaft and the intermediary body. It may comprise a spring such as a coil spring, or a resilient member such as a rubber block that acts between the intermediary body and the threaded shaft.

A damper may be provided to damp movement about the degree of freedom. This may act between the threaded shaft and the intermediary body, or may act upon the resistance means. The resistance means may bias the pedal or handle to a neutral position in which it is midway along its possible range of travel about the at least one degree of freedom.

The additional degree of freedom may allow a rotational movement or a translational movement of the axis of rotation of the pedal relative to the crank.

The intermediary part may comprise a body that is attached to the threaded shaft and that includes at least one threaded opening which is offset from the threaded shaft which receives a threaded pedal spindle that secures the pedal to the body. The axis of rotation of the pedal is therefore offset from the axis of rotation of the body part relative to the crank by the amount of offset of the threaded opening. In this arrangement, the resistance means may act against relative rotation between the body part and the threaded shaft. The movement felt by a rider with an imperfect pedalling action will be a rotation of the body part relative to the threaded shaft.

In an alternative it may comprise a body that is located within a recess, or bore, in the end of the crank, and which is supported by a bearing race located between the crank and the body that permits the body to rotate within the recess or bore if the pedal force is along a path which is not optimal. The body may comprise a generally disk shaped body, with a threaded bore which is arranged to receive a pedal spindle that lies offset from the axis of rotation of the disk shaped body.

The device may include a means for biasing the body into a neutral position relative to the crank whereby the pedal spindle and threaded shaft of the body (or the centre of rotation of the body where a threaded shaft is not used) lie on an imaginary line that is perpendicular to a line that connects the axis of rotation of the crank to the axis of rotation of the body. This way, the pedal will always lead the crank by 90 degrees as the crank rotates unless an imperfect pedal action is used. In that case, it will move away from 90 degrees once the resistance means is overcome, optionally producing the audible click that indicates poor technique.

When in the neutral position, the removable training device may locate the pedal at the same distance from the crank axis as it would be located if it were connected directly to the crank. This maintains the effective crank length, eliminating the need for a rider of a bicycle to which the crank is attached to adjust their saddle height.

The intermediary body may include an indication marking, such as a line or groove or ridge that extends between the threaded shaft and the offset threaded bore to enable easy identification of correct/incorrect technique to be observed. This line should, ideally, be orthogonal to the axis of the crank under perfect pedalling forces.

The intermediary body may include two or more offset threaded openings, each one arranged to receive a pedal spindle, and each one at a different distance from the threaded shaft. An indication marking may connect each one to the threaded shaft. The rider may chose to locate the pedal at any of the positions by adjusting the biasing means to create a neutral position that matches the chosen pedal position.

In this embodiment, the intermediary body in effect forms a secondary crank secured to the primary crank of the bicycle.

In an alternative, the intermediary body may comprise a guide part that is secured to the crank by the threaded shaft so that it cannot rotate relative to the crank and a slider which is free to translate relative to the guide part along an axis parallel to the axis of the crank, the slider including a threaded opening which is adapted to receive a pedal spindle.

In this alternative arrangement imperfect pedal technique will produce a translation rather than a rotation which can be felt by the rider. Again this may be opposed by a resistance means which may create an audible click as required.

The device may be constructed so that the slider is biased to a central position within the channel using a biasing means. The slider will therefore only be moved if a force is applied along the axis of the crank. Where a resistance means is provided that resists movement until a predetermined amount of force is applied it will also need to be a sufficient force to overcome the resistance means.

Two springs may be provided, one either side of the slider, to bias the slider in the neutral, position when under no load. The springs may form part of the resistance means. A flexible pointer may be provided which sits in the neutral position in a grooved slot on the slider and forms part of the resistance means, the pointer becoming deformed and eventually moving out of the slot whilst producing an audible click once a predetermined force has been applied.

The two springs may be adjustable to vary the resistance. Similarly, the device may be provided with two or more interchangeable pointers, each having a different resilience so as to vary the resistance to movement. The more resilient the pointer the harder it is to force it out of the slot.

The training device may therefore be arranged so that deviation from the neutral position will result is an audible ‘click’ and an abrupt movement of the pedal with respect to the crank. This helps the rider identify problems. The click may only occur once a predefined resistance is overcome.

The device may include one or more sensors which measure the relative position of the device and the crank. The sensor may comprise, for example, a rotary potentiometer that measures the relative rotation of the crank and the intermediary body. The deviation from the optimum position may be measured by the sensor and a processing means may be provided which receives the output of the sensor and processes the output to provide a drive signal for an electronic display (acoustic or audible or both), the drive signal causing the display to vary according to the amount of movement of the device along the additional degree of freedom.

The display may, for instance, comprise one or more lights which sequentially illuminate the greater the movement about the degree of freedom. The rider can the concentrate on reducing the number of lights that are lit up, or the relative duration that the lights are lit up during a revolution of the cranks, as a way of improving technique.

The intermediary body may be integrated with a crank or may be designed so that it can be easily removed from or attached to a standard crank.

The training aid may be arranged so that the pedal can be released from the intermediary part, allowing the pedal to be swapped for an alternative pedal. This allows the training device to be shared between riders who may prefer different types of pedal.

In fact, in a second aspect the invention provides a training device which include connection means for connecting the device to a pedal to form a removable training aid according to the first aspect of the invention.

Alternatively, the pedal may be secured to the intermediary means in such as way that it cannot readily be separated. Whilst this is less convenient it may prove beneficial in allowing the overall size of the training aid to be reduced, ensuring that the lateral spacing between the riders foot when secured to the pedal and the crank is optimised.

According to a third aspect the invention provides a combination of an exercise apparatus, such as a bicycle, or a stationary exercise bicycle, having a pair of cranks secure to a bicycle frame through a common axle, and at least one training aid according to the first aspect of the invention secured to one of the cranks.

The combination may include two training aids, each secured to a respective one of the cranks of the human powered vehicle.

The bicycle may comprise any known type of bicycle. For example the term bicycle can be construed to cover a stationary exercise bicycle, a road bicycle or an offroad bicycle, such as a mountain bicycle.

There will now be described, by way of example only, three embodiments of the present invention with reference to and as illustrated in the accompanying drawings of which:

FIG. 1 is a view of a conventional prior art crank and pedal assembly for a bicycle;

FIG. 2 is a view of a first embodiment of a training device that can be secured to a crank and pedal to form a removable training aid in accordance with an aspect of the present invention;

FIG. 3 is a view of two of the devices of FIG. 2 connected to a crank of a bicycle;

FIG. 4 is a view of a second embodiment of a training device that can be secured to a crank and pedal to form a removable training aid in accordance with an aspect of the present invention;

FIG. 5 is a view of the device of FIG. 4 connected to a crank of a bicycle;

FIG. 6 is a view of a third embodiment of a training device that forms an integral part of a crank and that can be combined with a pedal to form a removable training aid in accordance with an aspect of the present invention; and

FIGS. 7( a) to (c) are views of a resistance means which is included in the aid of FIG. 2.

FIG. 2 shows a first embodiment of a training aid 100 for a bicycle. It comprises an intermediary body 10 in the form of a plate and an attachment means 6 for attaching the body to a crank. In this embodiment the attachment means comprises a shaft which hats a thread at one end and an extended portion that is supported by a race 7 of bearings that run within a bore 7 a located towards one end of the plate, and three threaded bores 8 which are offset from the threaded shaft by different distances. As shown the uppermost bore is offset by the greatest distance, and the lowermost one is offset by the least distance. The threaded shaft is sized so that it can be threadedly secured within the threaded bore of a crank arm, where the spindle of a pedal would otherwise be located. Each of the three threaded bores in the main body can receive a spindle of a pedal, and as such are the same diameter and thread pitch as the threaded bore in the crank.

FIG. 3 shows the plate and shaft secured to a crank 3 prior to the addition of a pedal, which is omitted for clarity. The training aid in effect forms a removable secondary crank secured to the main crank and provides an offset between the axis of rotation of the pedal about its spindle and the long axis of the crank.

The training aid also includes a resistance means that acts between the threaded shaft and the body and which prevents relative rotation of the body and the threaded shaft during ideal pedalling action. This can be overcome if the rider applies a sufficient force in a direction that is not ideal and at that point the bearing enables the main body to rotate about threaded shaft where it is attached to the crank, and as it does so the relative position of the pedal axis and the crank will change. When. the rider is applying force at an optimal 90 degrees to the axis of the crank, the pedal spindle will be located ahead of the crank and at approximately 90 degrees to the crank axis.

The resistance means is shown in detail in FIG. 7 of the drawings. It comprises a cam surface 11 formed around a part of the perimeter of the extended portion of the threaded shaft 6 that is located within the body 10 and a cam follower 12 located within the body 10 that faces the cam surface. The cam surface 11 comprises a noticeable detent 13 corresponding to the ideal orientation of the main body 10 relative to the crank 3. The cam follower comprises a ball 14 that sits in this detent, and is biased into position by a coil spring 15. The amount of bias can be adjusted by a screw 16 which engages and end of the spring. Also shown in FIG. 7 is a modified intermediate body. This comprises a two part arrangement for the intermediary body, with a rotationally adjustable part 10 a being attached to a secondary part 10 b which in turn carries the cam follower. The adjustable part has three slots 17 and bolts 18 pass through these to secure the adjustable part to the secondary part. This two part arrangement enables the alignment of the body to be correctly set once the threaded shaft has been, tightened in position on the crank, giving the correct alignment of the pedal relative to the crank before use, by loosening the bolts and moving them along the slots as needed.

The location of the follower in the indentation of the cam surface lightly biases the body at the correct ninety degree to the crank position line and serves as an initial locating device for the optimum position. If the rider technique is not correct, such that the force they exert on the pedal is not perpendicular to the crank line the device will rotate about the threaded shaft. This rotary motion will cause the cam to progressively move out of the indent and to deform slightly. The followed therefore acts as a resistance means, resisting the riders force that is attempting to move it out of the ident. When the cam does eventually drop out of the indent the ride will be alerted of this by an audible click as the follower relaxes and a sudden movement.

Other methods of identifying faults in technique are possible. As shown in FIG. 2 grooves 19 are provided which extend from the bore to the threaded shaft which enable a trainer to watching the pedalling motion either on a live stream or recorded using a camera. Each bore is painted to define a straight line of bright colour between the threaded shaft centre 6 and the various pedal positions on the secondary crank will make identifying incorrect technique easier. These marks can be provided on the inside face of the main body, e.g. the one facing the crank, as they would otherwise be obscured by the pedal and riders shoe.

An alternative embodiment of a training aid 200 is illustrated in FIG. 4. This differs from the first embodiment in that it creates a linear movement of the pedal relative to the threaded shaft when the rider is pedalling inefficiently, rather that a rotation.

The alternative embodiment comprises a guide 21 which is fixed to a threaded shaft (not shown) that secures it to the crank, or is an integral part of the crank. A slider 22 is provided which fits within a channel formed by the guide that runs parallel to the crank axis. The slider is provided with a threaded bore 23 that allows it to be secured to the spindle of a pedal. Two springs 24 a, 24 b are provided inside the channel, one on each side of the slider 22, to bias the slider towards a neutral position in which both springs counter the force applied by the rider. In use, a pedal force created by a rider in a direction parallel to the crank axis will cause the pedal to move relative to the crank, providing an indication of poor technique.

A flexible pointer 25 secured to the slider sits in a grooved slot 26 on the guide when the slider is in the neutral position. The pointer resists any force that tries to cause it to leave the slot until such point that this force is exceeded. Thereafter it snaps out of the slot and any displacement can be felt as a sudden jolt and also as an audible click.

The applicants have appreciated that the attachment of the intermediary body to the crank and then to the pedal will increase the Q factor of the overall crank and pedal assembly, and is determined in part by the width of the axle that supports the cranks, the thickness of the cranks arms and the location of the pedal on the pedal spindle.

A third embodiment 300 of the invention which does not increase the Q factor is illustrated in FIG. 6 of the drawings. In this embodiment, the intermediary body 30 is integrated with a crank. The crank has an enlarged portion 31 at its free end which includes an annular bore 32 that extends right through the crank (it could be a closed bore in some arrangements). An intermediary body 32 which comprises a disk is located within the bore, and a bearing race 33 is located between the disk and bore so that the disk can rotate in its plane about its central axis. A threaded bore 34 that can receive a pedal spindle is located on the disk a distance from the axis of rotation of the disk. A resistance means, not shown, but which could be similar to that used in the first embodiment, resists rotation of the disk but allows it to rotate if the pedal action is not perfect. If a perfect action is used the disk will not rotate because the line of the force will pass through both the pedal spindle and the centre of the disk 32. 

1. A removable training aid for a human powered vehicle of the kind in which a pair of opposed cranks are provided which rotate relative to a common axis, the aid providing an audible or tactile indication in the event that a rider is rotating the pedals by applying an incorrect pedalling technique, the removable training aid comprising an intermediary body, attachment means for attaching the body to at least one of the cranks and a pedal secured to the intermediary body, the removable training aid being arranged so that in use the pedal is free to rotate around an axis of rotation that is parallel to the common axis, the intermediary part permitting movement of the axis of rotation of the pedal relative to the crank through at least one degree of freedom in the event that a force is applied to the pedal along a path that is not perpendicular to an imaginary line that connects the axis of rotation of the crank with the threaded bore in the crank, and in which the attachment means comprises a threaded shaft that in use engages a threaded hole in the crank and the body includes at least one threaded opening which is offset from the threaded shaft which is arranged to receive a threaded pedal spindle that secures the pedal to the body.
 2. (canceled)
 3. The removable training aid of claim 1 which includes a resistance means which prevent movement in the additional degree of freedom unless the component of the riders pedalling force applied is sufficient to overcome the resistance means.
 4. The removable training aid of claim 3 in which the intermediary body is arranged so that there is no movement of the pedal about the additional degree of freedom if a force is applied to the pedal which is orthogonal to this degree of freedom.
 5. The removable training aid of claim 3 in which the resistance means is arranged to substantially prevent movement about the additional degree of freedom until the force applied by the rider to the pedal in that direction exceeds a predetermined level, the movement thereafter being sufficiently large that it can be felt/heard by the rider.
 6. (canceled)
 7. The removable training aid of claim 3 in which the resistance means comprises a spring such as a coil spring, or a resilient member such as a rubber block that acts between the intermediary body and the threaded shaft.
 8. (canceled)
 9. The removable training aid claim 1 in which the threaded shaft and the threaded opening have respective axes that are offset from each other so that the additional degree of freedom allows a rotational movement of the axis of rotation of the pedal relative to the crank.
 10. (canceled)
 11. The removable training aid of claim 1 which includes a means for biasing the body into a neutral position relative to the crank whereby the pedal spindle and threaded shaft lie on an imaginary line that is substantially perpendicular to a line that connects the axis of rotation of the crank to the threaded shaft.
 12. The removable training aid of claim 7 in which the intermediary body includes an indication marking, such as a line or groove or ridge that extends between the spindle and the offset threaded bore to enable easy identification of correct/incorrect technique to be observed.
 13. The removable training aid of claim 1 in which the intermediate body includes at least two offset threaded openings, each one arranged to receive a pedal spindle, and each one offset by a different distance from the threaded shaft whereby a rider may choose to locate the pedal at any of the positions.
 14. The removable training aid according to claim 1 in which the intermediary body comprises a guide part that is secured to the crank by the threaded shaft so that it cannot rotate relative to the threaded shaft, and hence the crank, and a slider which is free to translate relative to the guide part along an axis parallel to the axis of the crank, the slider including a threaded opening which is adapted to receive a pedal spindle.
 15. The removable training aid of claim 10 in which movement of the slider is opposed by a resistance means which creates an audible click when moved. 16-17. (canceled)
 18. The removable training aid of claim 11 which includes two springs, one either side of the slider, to bias the slider in the neutral position when under no load.
 19. The removable training aid of claim 11 which includes a flexible pointer which sits in the neutral position in a grooved slot on the slider, the pointer becoming deformed and eventually moving out of the slot whilst producing an audible click once a predetermined force has been applied.
 20. (canceled)
 21. The removable training aid of claim 1 which includes one or more sensors which measure the relative position of the body and the crank, in use the deviation from the optimum position being measured by the sensor, the aid also including a processing means which receives the output of the sensor and processes the output to provide a drive signal for an electronic display (acoustic or audible or both), the drive signal causing the display to vary according to the amount of movement of the device along the additional degree of freedom. 22-23. (canceled)
 24. A combination of an exercise apparatus, such as a bicycle, or a stationary exercise bicycle, having a pair of cranks secured to a bicycle frame through a common axle, and at least one training aid according to claim 1 secured to one of the cranks. 25-26. (canceled)
 27. A method of training using an exercise apparatus according to claim 15 which comprises pedalling the bicycle against a resistance and observing any tilting movement of the rider's pelvis during the complete pedal stroke is an indication of poor technique causing movement of the pedal relative to the crank along the path of movement corresponding to a pedal force applied in a non-optimal direction. 